The invention concerns an applicator for application of coating color on a paper web, specifically a roll applicator.
Applicators of this general type are known from DE 36 05 409 A1. This device is intended to produce a uniform coating.
Problems occur with such applicators especially in the wedge-shaped entrance zone between the applicator roll and backing roll, particularly at high speeds, but also in the exit zone, before the paper web provided with coating color reaches the doctor blade. The doctor blade must fulfill decisive functions here. It is to contribute to producing a continuous and relatively thick layer which is completely smooth and free of doctor blade striae. Various types of doctor blade are conceivable, for instance with a stiff blade, with a bent blade which in its end area tangentially makes intimate contact with the coated paper web, and roll doctors. The equipment expense for such doctor systems is quite considerable. Nonetheless, the doctor devices known so far have not met demands in terms of coating quality.
The problem underlying the invention is to so design an applicator for application of coating color on a web that the coating quality will be further improved, particularly with regard to the smoothness of the coat, continuity of the coating surface and with regard to the sensitive dosing of the coating weight, all at a reasonable cost.